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Why are commercial flights not equipped with parachutes for the passengers?
I understand that commercial flights are equipped with life vests. I also understand that most military jets are equipped with ejection seats. It may be costly and technically challenging to equip passenger planes with ejection seats. Having seen air-borne personnel lining up and parachuting out of a C130, what is preventing flights from equipping each passenger with a life-saving parachute? Is it very technically challenging for an untrained person to deploy a parachute, or are there other reasons?

Maybe because of blackouts (oxygen suffocation), redout (spinning too much in the air) and responsibility (better put it on the pilot and crew, who can be trained extensively, rather than the passengers?). Disclaimer: I am not working in the field.

@QuestionOverflow I've reverted your edit with the point/counterpoint discussions - You raised some excellent discussion points, but please provide those "counterpoint" arguments in the comments under each answer (that's what comments are for). The goal of the Q&A format is to keep the question as a question, not a discussion of the answers (see http://aviation.stackexchange.com/about & http://aviation.stackexchange.com/help/how-to-ask) Thanks :-)

A better solution would be to have parachute system that protects the entire aircraft.Price out the cost of ejector seats.

See also this question, which has a detailed answer on the use of parachutes: What items could you bring on-board to maximise your chance of survival in an emergency?

While there are lots of info about parachutes, I added my answer to clarify about ejection systems. http://aviation.stackexchange.com/a/2342/1524

Related: Are parachutes allowed on airplanes as cabin baggage?

@NoahSpurrier Jet parachutes are impractical.

There are small planes that in case of emergency the pilot can deploy a parachute that can bring the whole plane down without the need of anybody jumping. Why can't this be used for commercial planes as well? To me it seems more plausible than all passengers to jump. see this vid: https://www.youtube.com/watch?v=DX-QUVen9Ng

it looks like some aircraft do now have "whole aircraft" parachutes!  http://robbreport.com/aviation/cirrus-aircrafts-vision-sf50-personal-jet-completes-flight-testing-video

Maintenance costs would be significant since parachute would probably need to be repacked by appropriately rated parachute rigger every 180 days (see FAR 91.307 as well as this question: Do unused parachutes need to be repacked? If so how often and why?).

Even if you could put ejection seats in passenger airlines, it wouldn't be a good idea. In order to prevent you from getting hit by aircraft parts, they have to push you out with some incredible force. I don't just mean you'll have a sore bottom for a few days. I mean your neck will snap if it's not perfectly straight, and you will get serious and permanent damage to your spine even if the ejection goes flawlessly.

This wikipedia article lists a handful of cases in addition to the famous DB Cooper incident where people have parachuted from an airliner successfully-- https://en.wikipedia.org/wiki/Airstair

So everyone gets a parachute? except the 90 year old grandma, and the 3 year old twins and the man who just had triple-bypass surgery and the disabled war veteran missing an arm and a leg, but everyone ELSE gets a parachute. (those were other pax on a flight recently taken)

Qualification: I worked at a sport parachute center as an instructor for 10 years and I hold an FAA Master Parachute Rigger certificate. I believe that qualifies me as an expert on the subject.
The majority of the above other statements here are correct. In summary:

The door of a pressurized passenger plane cannot be opened in flight for the stated reasons.
the door of most larger passenger planes cannot be opened in flight after you depressurize the cabin because they swing forward. Push a sheet of plywood against a thunderstorm-grade wind and see how well you do. Now multiply the wind speed by 5.
even if you blow the door out with explosives, the chances of an orderly exit are slim. At airliner speeds an orderly exit is critical if you expect to survive the jump. Street clothes will be torn to shreds. Oh, and it's COLD up there.
you cannot depressurize an aircraft over 12,000 feet altitude without the passengers passing out rather quickly. If you can control the plane down to this altitude, you don't need the parachutes.
it is extremely difficult to exit an unstable aircraft that is built for sport parachuting (in-flight door, suitable handles, door already open). If the plane is spinning and you are beside the door you might get tossed out and then struck by other parts of the airframe. If it's a larger plane and the door (or you) are away from the current axis of rotation, good luck. Yes, jumpers have successfully exited a crippled jump plane. None of them want to try it again.
modern sport parachutes use steerable ram-air canopies. Jump one of these without any training and you will hurt yourself landing. Most emergency parachutes are round. Jump one of those without any training and you will break something when you land. 200 untrained people jumping ram-air canopies all at once will result in a number of collisions and entanglements, which are typically fatal for all involved.
exiting an airplane below 1000 feet is really not practical. I would do it IF a) the plane is currently under control; b) landing is not practical; c) It's really 1000 feet, not less; d) I'm sitting beside the door. Possible scenario is the engine goes boom and I know there's nothing but rocky land ahead of us. Of course my gear is already on my back ready to go, and I know how to use it.

There have been many cases of a jump plane experiencing engine problems on the way up. By the time the pilot turns around, the cabin is usually empty. There have also been cases where jump planes have crashed on takeoff. None of the (very experienced) jumpers on board thought about anything other than tightening the seatbelt.
Points I disagree with: (although they do not change the outcome)

Emergency parachutes (seat-pack types) are available for far less than sport rigs. Maybe $1,500 each. Weight around 8-10kg. Putting a purpose-built one on would be not much more complicated than a 4-point harness. This was seriously considered back in the 1950's - aircraft seats were designed with parachutes built in. Planes were neither pressurized nor fast back then. Think DC-3 era - the DC-3 makes a great jump plane, I have used one a few times.
maintenance costs would be no more than the escape slides, flotation gear or other similar equipment.

Thanks for your input. One quick question. If the airplane is tearing up in mid-air and plunging towards the ground in 1 or 2 min, would you prefer the parachute option or the seat belt option?

@QuestionOverflow If the plane is tearing up in mid air and plunging towards the ground, the preference is academic: you're going to die.

What he said. If the plane has suffered catastrophic failure (e.g. mid-air collision) your chances of survival IN the plane are zero. You have a moderate chance of being chopped up by the propeller (all jump planes use props). If you get away from the plane it's just another skydive. The pilot will be right behind you. Our pilots generally had zero interest in jumping, all said they would bail if the plane was uncontrollable.

@DavidRicherby I think the point Question Overflow is getting at is that most people would prefer a .0001% chance of survival to a 0% chance of survival.  Yeah, the odds are rather long, but having a parachute would at least, minutely, improve the chance of survival.  ...I think the real question we ought to be asking is this: is anyone willing to spend $200 extra  a flight so planes can carry the parachutes, train the staff, train the pilots, make better walkways (etc) for something that is extremely unlikely to happen.  Assuming it would even be that cheap?  My guess, honestly, is no.

I choose your answer because it is backed up with some facts to prove that it isn't that costly for flights to be equipped with parachutes. Without running experiments and doing probabilistic studies, how confident are we to say that the survival rate would be 0.0001% and not 1% or even 5% when such an emergency situation occurs. Do we then discount this equipment just because many people would not get a chance to use it?

Out of interest, what's up with 12,000 feet ? Is there is margin of the air layers or something

@QuestionOverflow: Any safety system is a balance of need, cost, and success rate. Putting parachutes in passenger planes will have an insignificant success rate at a moderate cost. It's insignificant because planes crash in situations outside of do-able bail-out parameters. Lets re-ask your original question as "Why are commercial flights not equipped with ejection seats?" Martin-Baker make excellent ones, and I will pay good money to watch an entire 777 punch out.

@QuestionOverflow Please remember that this is not a discussion site.

@AyeshK: 12,000 feet is a standard jump altitude for several reasons: it is easily reachable by a single-engine Cessna (most common jump plane), high enough to provide 60 seconds of freefall, and not so high you need supplemental oxygen onboard or interfere (much) with commercial air traffic. The highest I have jumped is 16,000 feet - the airport looked really small and I was a bit bored on the way down. The air is noticeably thinner (and colder) up there too. High-altitude drop zones like Denver CO often stop at 9,500 feet.

Even a B-52 bomber has ejection seats for only a few lucky crewmembers. The rest have to put on a pack and get out an exit.

With increasing body sizes many people would not be the appropriate shape and weight for most parachutes. Even if you put a round canopy in them, a 350 pound passenger is not going to fare well under a 24' conical. What would you do for an infant? Toddler? Child? The TSO certification for a low speed parachute is not going to handle 400 kts anyway. I did a tailgate exit from a skyvan at 180mph and it was "very brisk". I would not choose to make a 250mph exit much less twice that speed!

United 232 might have had more survivors if it had been equipped with parachutes.  The airplane was almost controllable, as evidenced by the fact that two-thirds of the passengers survived the crash-landing, so the "exiting an out-of-control aircraft" issue wouldn't be present.  Still, that's the only case in the entire history of jet aviation I'm aware of where parachutes might have helped.

@PhilPerry and the pilot would do his utmost to slow the aircraft down as much as humanly possible, and keep it level, while the crewdogs try to open the exit hatch in the bottom (which opens inwards) and jump out. Survival rate for them was estimated to be greater than nothing but not much greater, everyone involved knew that and from what I read more than a few crews decided they'd rather go down together than have some people plummet to their deaths while the rest used the ejection seats.

Parachutes are heavy, expensive, difficult to use and will be useless in pretty much any air disaster.
In order to parachute from a commercial aircraft it would need to be

in a stable attitude,
at low speed
and below about 12 000 ft.

Short of an aircraft losing power to all engines like the Gimli Glider, in which case ditching in the ocean or finding an open space to land is preferable to parachuting your passengers out, I can't think of any other catastrophic failure that would give you the opportunity to let passengers leave by parachute.
That's aside from the difficulty of trying to get passengers, most of whom are panicking, to properly don a parachute and tighten the necessary straps. With a lifejacket a person can still hold onto it in the water if they didn't do the straps right, but the same is not true for a parachute.

Can you provide some data to backup your assertion? Weight of a parachute backpack? Cost of one parachute? There were historical anecdotes of crew being able to bail out of their bombers crippled by enemy fire. How complicated is it to put on a parachute backpack, especially when a safety demonstration can be shown before takeoff? Granted that there would be panicky passengers and not all would survive, if the parachute is deployed at a sufficient height, wouldn't the survival rate be higher than a high-speed crash?

Also, you're presumably going to end up with your surviving passengers spread over a rather large area. For every minute your evacuation takes at 150kt, your passengers are spread over a 2.5nmi length, even if they fall straight down. Standard evacuation times won't apply since (a) you can only use the rear doors and (b) a significant proportion of the passengers will need some persuasion to jump. And, as alluded to by the answer, if you can fly your plane slow and level enough for parachuting, it's probably in good enough shape that you don't need to evacuate.

@QuestionOverflow Trivial Googling suggests that a parachute backpack costs somewhere in the region of $6-8k and weighs 10-25kg (15-55lbs). So, for a 150-seat B737, you're talking somewhere around a million bucks' worth of parachutes, weighing 1.5-4 tons. Also, note that bomber crews are (a) trained and (b) small.

@QuestionOverflow What David said. There's a huge weight penalty incurred to carry a parachute backpack for each passenger.
The example of WWII bombers is a bad one, as those crews were well-trained on how to use their parachutes and put them on in emergencies, they flew in unpressurised aircraft at much slower speeds than modern airliners and were subject to very different types of accidents.

@davidricherby How if people are forced to wear parachutes during flight and then kicked out of the plane  in case of failure in plane.

@AdityaPatil Is that a serious question? If so, try this: you'll need a friend or two to help. Stand in a doorway with the door open away from you and place your feet against the wall, outside the door frame. Brace your hands against the frame at shoulder height. How long does it take your friend(s) to push you through the door while you're wedged against it like that?

@davidricherby  Can we tell the passengers, either you die in the plane or jump out in a sec?

@AdityaPatil that only works if people are thinking rationally.  In an emergency most people are going to panic and rational thought will not occur.

Also worth considering is the fact that most aircraft crashes don't actually kill people (most statistics show aircraft crashes with at least 100 fatalities - somewhere around 10 of those per year). As long as the plane didn't actually disintegrate (chute aren't going to help you there), the chances of survival aren't negligible - the overall rate is somewhere around 35%, including the cases where chutes wouldn't help either. So your best bet is to stay on the plane, unless you're a trained paradropper, especially since you're not landing on a prepared landing site - very hard.

Let's say you get the door open somehow, and the plane depressurizes.  Useful consciousness is measured in seconds at 36,000 feet.  That's why the standard instruction is to put your mask on first, then help those around you next when you are given the O2 mask briefing.  So in addition to the parachutes for every passenger you would need a portable O2 system for each passenger (and train them how to don it and use it) if the pax need to leave their seats and shuffle towards the open door.

The main reason that parachutes are not used is that there are very, very few aircraft accidents that occur with enough time to actually use one.  In fact, I'm not sure that there have been any.  Below are a couple examples that you may originally think that parachutes could have been useful on because they initiated from a high altitude.

Air France 447:
The short version is that they stalled the airplane at cruising altitude and held it in the stall until it crashed into the ocean.
Let's consider that the amount of time from the peak altitude of the aircraft until impact with water was only 3 minutes and 21 seconds.  Let's be very generous and say that everybody on board immediately knew that the aircraft was going to crash and there was nothing that the pilots could do.
This gives the panicking passengers just over three minutes to get their parachutes out of storage, properly secure themselves into the harness (which, trust me, isn't as easy as it sounds even if you know what you are doing and are in the proper frame of mind), all while in the confined space of an aircraft seat with everyone else around them doing the same thing.  After that, we somehow need to open the doors and get people to orderly line up and exit the airplane without freaking out and getting scared.
Seriously, 99% of the people won't even get their parachute on (correctly) in that amount of time, much less the far less time that they would really have before they knew about the crash.
The reality of the matter is that the pilots are doing everything possible in an emergency situation to not crash in the first place, and if they are successful (which they usually are) then having everybody jump would have caused many more problems than having the passengers stay put in their seats with their seatbelts on.  In this particular crash, the pilots didn't even realize that the crash was certain until four seconds before impact when one of the pilots verbally stated "we're going to crash".  Up until that point they were focused on recovering the aircraft and probably would never even have given the evacuation order had it even been available.

Gol Transportes Aéreos Flight 1907
This was the mid air collision over Brazil.  At least in this case, it became certain pretty fast that the aircraft was out of control and was going to crash.
A small quote from the accident report describes what happened immediately after the collision:

Immediately after the collision, PR-GTD started a fast descending
spiral, similar to the  maneuver known as spin, which by no means
could be recovered or controlled by the crew.  During the vertiginous
dive, the aircraft was submitted to extreme aerodynamic forces,
around all the axes, with positive and negative accelerations, well
above the maximum  resistance limits of the operational envelope. As a
result, there was an in-flight break-up of the aircraft in several
pieces of different sizes, which hit the ground.

The increased G forces on the airplane were very likely to the point that people couldn't stand, or at the very least would have a much harder time doing so.  Trying to put a parachute on in these circumstances would be even harder than in the previous example.  Total time from the mid air until impact with terrain:  Estimated 1 minute 5 seconds.

Each of these scenarios assume that even if there were parachutes on board and people were able to don them correctly in time, that they would be able to use them to survive. Here are a few additional factors that would come into play in the unlikely event that they were able to even get to this point:

Many modern aircraft doors can not be opened in flight.
If this happened at high altitudes, everybody would need oxygen as well or they would pass out.
The passengers that actually make it out of the airplane do not know how to fall in a stable position, and the parachute is very likely to become tangled while opening as they are tumbling through the air.
The passengers would need to actually deploy the parachute manually while most probably in a panicked state of mind.
There would be many injuries during landing.
Once they did land, they would have no survival gear.  This is particularly a problem over the open ocean or in the jungle (where these flights have been).

Considering that even in most accidents the aircraft is still landed in a somewhat stable manner and most people survive, having a couple hundred people bailing out of an aircraft would most likely cause more harm than good, even if they could solve all of the technical issues.  If the decision is made to evacuate and then the pilots get the aircraft back under control, it would be even worse!

I'm no expert, but don't your times also skip minimum altitude required for the 'chute to open?

@AllenGould Absolutely, but you really only need a few seconds for an emergency parachute to open. My point is that even if you had all of that time available, it still wouldn't do any good.  :)

Also, the problems with AF447 started when they flew into a thunderstorm. Jumping out into one of those would probably introduce even more problems to the equation.

You could possibly add the 1996 collision near Delhi to this list: the Ilyushin seems to have stayed airborne and intact for a little while.

@DavidRicherby Yeah, it sounds similar to Flight 1907 above in that they went into an uncontrollable spin....  :-(

Another example is the "Miracle on the Hudson" USAir 1549. They were in stable flight and possibly had enough time to don parachutes and exit (4 minutes after bird strike, much less after deciding teterboro was unreachable), but were not high enough to deploy (as it briefly reached ~3000 feet).

I would agree there are very few instances where parachutes would be practical, but complete hydraulic failure accidents such as United 232 or JAL 123 are examples where passenger parachutes might have been a practical option.

Almost all fatal accidents happen during take-off or landing, where parachutes would not be of any help.
If the accident happens at a higher altitude, and the aircraft is still more ore less flyable, it is much less risky to attempt an emergency landing and save most or all of the passengers, than risk parachuting them (the other answers have plenty of reasons why it's risky). If the aircraft can't maintain speed and altitude, you don't have the time to parachute even cooperating passengers, much less panicked ones.

Using a parachute is not a easy job. It require large amount of training, even well trained army para units face more casualties during para jumping. The key odds for using parachute in a commercial airline are

Untrained personal using a parachute is much more risky and it may not serve the purpose of saving the life. We may not expect all the passengers of a commercial airliner to have attended a para jumping trainings.
Jumping from an airliner at higher altitude requires supplemental oxygen and requires special training.
Cost of a parachute is much higher. So, this would increase the cost of ticket and the benefit out of it is significantly limited. This would not be economically possible.
The parachutes need to be maintained periodically. Maintaining few hundred parachutes per aircraft would increase the ideal time of the aircraft which leads to cost overruns.
It would be literally impossible for children’s, peoples with disabilities to use the parachutes.
Opening a pressurized cabin at a higher altitude would result in a decrease in altitude due to heavy inflow of air and would make the situation even worse.
Parachute jumping needs a stable platform and a steady aircraft. But, in a commercial airliner which is in dangerous conditions it is practically impossible.

And don't forget that parachutes are pretty much useless to people of over about 200lbs, which is a pretty large part of the adult male western population. They'd either need to be banned from flying or have to sign waivers, which isn't good marketing, and that for no benefit whatsoever.

A safety demonstration could be provided. 2. It is an emergency, the lack of oxygen is only temporary. 3. How costly is a parachute? 4. Life jackets also need to be maintained periodically. 5. At least people who have no disabilities can survive? 6. I agree with this point. 7. We are talking about an emergency scenario where it could be equally dangerous to stay in the doomed plane and do nothing.

@QuestionOverflow Lack of oxygen is temporary, sure. But the effects of lack of oxygen are much longer lasting!

@jwenting Any sources on the 200lbs assertion?

@jwenting Seconding kmort's request.  Paratroopers carry large amounts of supplies (food, weapons, ammo, etc) when they drop; I'd be shocked if most aren't well over the 200 lbs level.  My assumption would be that the 200lbs figure is a safety limit for a standard size commercial chute.  I also believe the paratroops fall faster and land harder than is normal for recreational jumping; which implies that (at the risk of more injuries from bad landings) there is a decent margin between commercial safety thresholds and going splat.

@DanNeely yes, it's probably a limit that can be stretched, but there's a limit (though you can land several tons using just parachutes if you make the chutes large enough and maybe add some shock absorbers). Doesn't mean you want to have an untrained person to that treatment, especially one who is likely to get seriously injured as a result (overweight people tend not to be very athletic, so just putting a flyer with proper landing technique in the emergency egress instructions isn't going to help either).

@kmort any offer for "trial jumps" and even jump lessons I've seen mentions roughly that as an upper limit for people who can apply. So it's a good assumption that it's a typical safe limit for commercially available parachutes designed to carry human beings.

@jwenting That's too bad. I'll have to lose some weight because I wanted to try it.

@jwenting The US Army uses parachutes that can cope with 360lbs (according to Wikipedia). Perhaps the 200lb limit for jump lessons is because they're tandem jumps at first?

@jwenting I've seen 240 lb. offered as the limit for recreational skydiving, which would include a much larger percentage of the population than 200 lb., though it would still leave out quite a large number of people.

Parachutes are also sized to the weight of the jumper.  It isn't a one-size-fits-all sort of item, so each passenger would need to be individually fitted with a chute before boarding, rather than just having them available in seats.

The jump limit that recreational skydiving drop zones use are a limit of the equipment that they have combined with the general concept that most people over that weight are out of shape and therefore are more likely to be injured and are more of a liability.  (Note that this isn't always true.  Bodybuilders can easily exceed this weight and are in very good shape, and some drop zones have gear for heavier people.)

They air drop humvees and several tons of gear from c130's pretty regularly... I am pretty sure that is considerably more than 200 or even 240 or even 440...

@Chad Sure, with a large enough parachute, you can drop anything. And I guess there's also the argument that those humvees sure as heck haven't been trained to parachute so it must be theoretically possible for untrained humans to do the same. On the other hand, the practicalities aren't good and humans are much more fragile than humvees.

@DavidRicherby Impacting the ground at 400mph+ is far less safe.  My point is simply that the weight and size restrictions provided in the comment are not valid concerns.  The logistics of making sure every flight had the properly sized and rigged chutes for all passengers is another story.

"Opening a pressurized cabin at a higher altitude would result in a decrease in altitude due to heavy inflow of air and would make the situation even worse." I don't think that point makes sense. Did you mean outflow of air?

The profit in aviation in 2013 was about \$11.7 billion, on \$708 billion revenues. So the profit margin in global aviation last year was about 1.6%. How do you expect that to work when you remove about 10% of the fare-paying passengers by replacing them with 8-10kg parachutes?
That is about \$70.8 billion you lose there, every year. Assuming it would save 240 lives every five years (I am being optimistic here), that's about \$1.5 billion per life saved. If you have that amount of money to invest, I can think of more efficient ways to make aviation safer than by adding parachutes which might help in a crash once every five to ten years.

to be fair, it wouldn't be 10% of paying costumers, it would be 10% of potential customers, the real number would be lower. But even if the number is reduced by half, your point still stands.

I disagree with your point. The cost could be recouped by a 10% increase in airfare if this is implemented across the board.

@QuestionOverflow You miss the point; the costs do outweigh the benefits by far, it is a waste of money.

There are several good answers above, but another important thing to consider is that it's impossible to jump out of a commercial airliner (except the 727, which is rarely still found in passenger aviation) while in flight, unless a hole has opened in the fuselage or it has otherwise become depressurized. The doors have to be pulled in to open, which is, for all practical purposes, impossible while the airframe is pressurized. From a safety perspective, the additional risk of allowing the doors to open in flight far outweighs the potential benefit of letting people bail out in the narrow range of circumstances that that would even be possible. This is because it would require the doors to open outward, which opens up the possibility of them blowing out in flight. Back when airplanes were designed that way, several people died from explosive decompression due to a door blowing out. This was a problem both on the DC-10 and on early 747s.
A further issue to consider is the locations of the exits. The reason that it was possible to bail from a 727 is that it had an exit in the tail cone. No other passenger aircraft that I'm aware of has that. Many military cargo planes (like the C-130 you mentioned) do use ramps in the tail, though, and that's where people jump out from in those aircraft. If you try to jump from a side door in a jetliner (which are the only doors that exist in most modern jetliners,) you'll likely be promptly cut in half by the horizontal stabilizers moving through you at 550 mph immediately after stepping out the door. Of course, this would also damage the horizontal stabilizer, which would then quite likely result in the death of everyone still on the plane, due to loss of pitch authority. Of course, if you jump out of a door in front of the wings, you might be killed by a wing or an engine rather than a horizontal stabilizer, but the results are still equally undesirable. Jumping out of side doors is possible (and normal) for the much slower aircraft used for skydiving, but not for a passenger jet moving 550 mph.
I don't have time at the moment to run all of the numbers, but one thing did come to mind that helps in the comparison: terminal velocity. Terminal velocity is the point at which the upward drag on a falling object is equal to the downward gravitational force and, thus, downward acceleration due to gravity stops. Where this provides some insight on this question is in the comparison of forces. Terminal velocity for a human is about 120 mph at low altitude. This means that the wind speed required to equal the gravitational force is approximately 120 mph at low altitude (of course, this can vary depending on the shape and mass of the person in question and their position relative to the airflow.) Since drag is proportional to the square of velocity and linearly proportional to air density, this means that a 550 mph wind at an altitude where air density was roughly $\frac13$ of at the surface would exert a force with a magnitude of about $(\frac{550}{120})^2(\frac13)\approx7$ times the magnitude of the gravitational force. So, at least initially, you'd be accelerated backwards about 7 times as quickly as you'd be accelerated downwards by gravity in these conditions. Aside from the fact that being accelerated backwards at around 7 Gs is going to hurt, there is a very real possibility of hitting any part of the aircraft that happens to be behind you. Also, as mentioned in a comment below, it would actually be entirely possible to be accelerated upwards (at least briefly) with that much drag, depending on the average angle at which your body is deflecting the wind stream. Another consideration is that the windstream itself will be faster than the true airspeed of the aircraft itself around certain parts of the aircraft, including around the fuselage and above and behind the wings. Furthermore, the airstream is not always exactly parallel with the aircraft. It can have an upward component relative to the aircraft around certain parts of the airframe while it almost always has a downward component relative to the aircraft behind the trailing edge of the wings. Also, if the plane itself is descending, there will be an upward component of the airstream relative to the aircraft at almost all points, except maybe right behind the wings. So, long story short, a lot of factors play into this, but things aren't looking up for the prospective jumper.

Pretty much your entire second paragraph is wrong because you are also moving forward at 550 mph and when you jump out you start to drop away kind in a manner similar to a bullet trajectory....

Wind. You may be moving forward at 550 mph at the moment you step out, but that isn't going to last long at all in 550 mph wind. You will be accelerated backwards very, very quickly.

Yes, but you fall very very quickly as well.  As a skydiver and pilot I can assure you that even when I have edited out of a side door and jumped and stretched and reached for the tail of the airplane, I never even came close because of the physics involved.  :-)

Have you ever jumped out at 550 mph? :) Remember that drag force varies with the square of velocity. It's not linear. If you're used to jumping at 100 mph, the backward force (and acceleration) you'd experience at 550 mph is roughly 30x what you're used to.

Have you? :-) You are making claims that I find hard to believe, if you have references that prove them then I'd love to hear what you have to say.

Ok, now you've made me more curious. - haha - I found a document where the U.S. Navy tested human subjects in wind tunnels back in the 70s to determine their aerodynamic characteristics. I'll see if I can run the numbers based on that later when I'm not at work. From a quickly glance, though, it looks like they only tested up to 144 knots (presumably due to the lack of desire to project the test subjects at high velocities into whatever happened to be behind them in the wind tunnel.) Here's the document link

Considering the horizontal force exerted is over an order of magnitude greater and the vertical force exerted by gravity is, for all practical purposes, exactly equal, I don't think this is going to end well for the jumper.

I know that at the world freefall convention they used to do high speed passes in a 727 at 250 KIAS, but they were jumping out of the back of the airplane.  I'm curious about the horizontal deceleration -vs- vertical acceleration though because I think you'd have a really hard time hitting the airplane since you have the same foward velocity initially and will fall away from the airplane at the acceleration of gravity (assuming that the aircraft is in level flight).

Yeah, that's why I mentioned the 727 as an exception above. Your initial forward and downward velocity relative to the aircraft is zero, so it just ends up being a matter of whether the gravitational force or the drag force ends up dominating when you first jump. Of course, it will also depend on the vertical position of the horizontal stabilizers (or wings, engines, etc.) relative to the exits. You might survive a jump aft of the wing in a T-tail if it didn't have tail-mounted engines.

The statement about inward-opening (plug) doors is incorrect. Boeing historically favoured plug doors, with some notable exceptions such as the 747 cargo bay door. However, Airbus doors open outwards, as (crucially to this discussion) do Boeing 777 doors.

@reirab Horizontal and vertical acceleration are independent. Vertically, you will fall literally like a stone, since the only vertical force on you is gravity. To demonstrate this, take two reasonably heavy balls (tennis balls are fine, just not something like ping pong balls) and roll one off a table. At the same time as the first ball leaves the table, drop the second ball from the same height. They'll hit the ground at the same time, even though one was moving horizontally and the other wasn't. (As I recall, this experiment is essentially due to Galileo.)

@DavidRicherby What you state regarding the vertical and horizontal accelerations is true, but that doesn't change anything that anyone said above. As I said earlier, the vertical acceleration (at least the part of it due to gravity) will be exactly the same regardless of forward airspeed. It's how that compares to the horizontal acceleration that will determine whether you could potentially hit part of the aircraft. The vertical acceleration will be (roughly) the same regardless of airspeed, but the horizontal acceleration actually varies with the square of airspeed.

@reirab OK -- I thought you meant something different by "it just ends up being a matter of whether the gravitational force or the drag force ends up dominating".

@reirab Don't forget that the human body will most likely produce considerable lift as well. The whole aerodynamic situation is quite complicated... I'd be quite interested to see a demonstration, I wouldn't be surprised if the person was actually pushed up for a second after the jump. And what about the low and high presure zones created by the plane itself?

@Luaan, Yeah, I thought about that, too, but didn't really want to go into it in what already turned out to be long comments. The amount of lift produced by your body itself would depend greatly on how your body is positioned relative to the airstream (actually, the horizontal acceleration would, too.) As far as the effects of the aircraft, the wing deflects the airflow downwards, so if you jump right behind the wing, that will probably help to accelerate you downwards, though the force vector it would apply would depend on aircraft type, airspeed, and position relative to the wing.

Actually you can jump out of the side of C-130 on static lines. It is done all the time.

Terminal velocity isn't relevant: it takes over five seconds to accelerate (at 1g) to 120mph even in a vacuum so it'll take even longer in air. Whether or not you hit the stabilizer of a plane after jumping out of it, it'll happen (or not happen) way sooner than 5s.

@DavidRicherby Earlier, we were trying to compute (or estimate) how the drag force applied by a given airspeed compares to the force applied by gravity. Terminal velocity is exactly that: a measurement of how much wind speed it takes to produce a force equal to the force applied by gravity at a given atmospheric density. Since we know how that force scales with airspeed and atmospheric density, we can then easily determine the ratio of the force applied by a given airspeed and air density to the force applied by gravity (since the latter doesn't change measurably.)

@DavidRicherby For what it's worth, in the atmosphere it takes about 10 seconds to accelerate to terminal velocity after jumping out of an airplane.  :)

@reirab: when a passenger plane is doing 550mph true airspeed, it is because it is at a height where the atmosphere is about a third as dense compared to sea level. If you would look at the speedometer at that moment, it would show about half that speed. Most aerodynamic characteristics depend on the indicated air speed, not the real one. Bottom line, you should use about half the speed in your calculations.

@MartinArgerami Excellent point, in fact indicated airspeed would typically be less than half of the true airspeed at altitude like this.

@MartinArgerami, The drag equation uses the true velocity of the object relative to the fluid, not the IAS. It takes the density into account and I mentioned its effect in my calculations. If not for the air being so much less dense, the force would produce about 21 gs of acceleration rather than 7 gs.

@DavidRicherby From what I've read, Airbus and 777 doors are still essentially plug-type: while they don't have to be pulled into the cabin to open, they do need to be moved upwards off their stops, and a pressure differential will result in far too much friction for a human to open the door.

@reirab: Indicated airspeed is the appropriate combination of true airspeed that appears in lift (and drag) equation. You can do the calculation with true airspeed and pressure at the altitude or with indicated airspeed (and normal density as just conversion factor) and get the same result.

To add a voice to the choir...
There are only two models of commercial airliner still in service anywhere that have an exit that would allow passengers to jump relatively safely; jumpers from practically any modern plane, like this 737NG, would face potentially fatal encounters with the engines, wings or tail surfaces attempting to exit from the sides of the aircraft in flight:

Those two aircraft are the MD-80 and the Boeing 727, which have a ventral airstair designed for use at airports without ground services like mobile ramps or jetways:

Most other large T-tails had ventral airstairs, but these two aircraft are the only ones left in service with any major U.S. commercial operator.
The 727 in fact was specifically chosen for a 2012 "crash test" of a commercial airliner, because it allowed the crew that flew it to the crash site to bail out the back ala D.B. Cooper, leaving the aircraft under remote control from a chase plane:

This experiment still doesn't reflect any real-world possibility for a fully-loaded plane to bail out prior to a crash, for the following reasons:

The 727 is no longer in service with any U.S. passenger airline (a few cargo carriers like DHL still have some serviceable 727 airframes), and American, the last major operator of the MD-80, is retiring the last airframes in the next couple of years, replacing them with B737s and A319s. If this retirement goes to schedule, there will be no airframes with ventral stairs in operation by any U.S. passenger line by 2018.
The rear airstair on "Big Flo" was heavily modified, all but removed actually, so that it would have negligible effect on the aircraft's aerodynamics when open (the airstair is not meant to be opened during flight, and in fact a wind-actuated lock called the "Cooper Vane" normally keeps the airstair from being opened when the aircraft is travelling at speed, a direct result of the D.B. Cooper hijacking).
The plane was on a stable wings-level descent at 130 knots, nowhere near cruising speed and slow even for approach speed.
A total of 6 people had to bail out of Big Flo, not the 100-plus people that would have to hit the silk in a fully loaded passenger flight.
Everyone on the plane knew it was going to crash years before they took off. If passengers had that kind of advance notice their flight would end that way, they wouldn't even get on.
Everyone on board was prepped and ready for their jump 30 seconds before egressing. Even giving that same time to every row of a fully-loaded jet instead of every 2 or 3 people, it would take a full 14 minutes to get everyone out of a fully-loaded 727. If you have that kind of time to orchestrate a bail-out, you don't need to.
Everyone wearing a parachute knew what they were doing. The copilot and flight engineer bailed in tandem jumps with master skydivers; the pilot and cameraman had their own skydiving certs and made solo jumps.
Everyone on board the plane was dressed for the occasion in flight suits that facilitated skydiving, with the actual skydivers wearing their chutes the whole time. No dresses or other baggy street clothes, and the only in-flight prep for the tandem jumpers was to hook the two harnesses together.
Other than the modified airstair and the fact it was past its rated number of pressurization cycles, there was nothing mechanically wrong with the aircraft (until it hit the ground of course).

So, in other words, nothing about the way the crew exited this aircraft prior to the crash would apply to your average passenger airliner. You might think bailing out of an aircraft gives you a chance, but if you don't know what you're doing with a parachute on your back, you'll be just as dead outside the plane as in. Considering that the most generous estimates say that only one in 20 people even do a tandem skydiving jump once in their lives, the percentage of people on board your average airliner who'd be likely to negotiate their way back to the ground with a parachute is a rounding error.

From basic high school physics, assume someone is 1.7m tall and steps out the plane rather than 'diving'.
The equation:
$$Distance~(from~standstill)=\frac12Acceleration\times{Time}^2$$
And substituting:
$$1.7m=0.5\times9.8m/s2\times{t}^2=0.59s$$
The panicked passenger would take 0.59 s for his head to be safely clear of any decapitating wires that happen to be level with the bottom of the door. If he immediately decelerated to 0 mph forward motion (I need someone else to figure out that part) he goes backwards 130 meters before he has dropped to safety. But even if it takes him 0.4 s to decelerate, that still leaves 0.19 s stationary in relation to the plane when his head isn't safe. That is about 42 meters, not counting the distance traveled while he is slowing down during those 0.4 s so I'm inclined to support @reirab on this one.

The terminal velocity of a human oriented perpendicular to the relative wind and spread out is somewhere in the neighborhood of 120 mph, so you might figure your worst case deceleration to use this forward speed and assume it happens instantly.

It turns out to be a lot more complicated than this because both the direction and magnitude of drag depends enormously on how your body is positioned relative to the airstream and because the airstream itself might not be exactly parallel to the aircraft depending on your jump location (it would be moving upwards over the leading edge of the wing and downwards aft of the trailing edge,) but this is good as a first approximation. Thanks. And, just to state the obvious, if you're exiting from behind the wing, you are within 40 m horizontally of the horizontal stabilizer on any current jetliner.

Is there a good reason why you choose 0.4s as the time it takes to decelerate and not 1s or even 5s?

@QuestionOverflow, Based on my computations above from the drag equation, the initial acceleration due to drag would have a magnitude about 7x the acceleration due to gravity. 1 g = about 32.17 ft/s^2, so 7 gs is about 225 ft/s^2. If we used the above equation for a constant acceleration, that would give us a backwards displacement of 39 ft in the 0.59s it takes for your head to drop below the level of the bottom of the exit door. The real displacement in the first 0.59s would be a bit less since the acceleration isn't constant (requires a diff eq to get the exact answer.)

However, the drop required to really be safe would depend largely on which door you exited from, the type of aircraft, and the attitude of the aircraft relative to the airstream. If you jump in front of the wing, you'd need to fall further to be safe in a normal commercial aircraft, since the bottom of the wing is usually well below the cabin exit doors. If you exit behind the wing, the distance you need to fall will depend on the position of the horizontal stabilizers and the attitude of the aircraft relative to the airstream, both of which can vary significantly.

@reirab, thanks for making the effort to do the maths. There are many factors at play. Whether a person would struck anything also depends on the configuration of the aircraft. Based on your calculations, we can't conclusively say that a person would meet certain death by bailing out from the aircraft.

@QuestionOverflow, Yes, as I said before, it would depend on a lot of factors, especially related to the particular aircraft and which exit door is chosen. For a typical airliner, though, I wouldn't advise trying it. The temperatures aren't going to be pleasant, either.

Prelude: While studying for being airplane engine engineer in university I took 3 years of special military course where been taught to be military aircraft mechanic. Also forgive my possible incorrect tech terms as English isn't my native language.
While here are plenty of great answers about parachutes with detailed explanations and facts about it, I'd like to add my 2 cents about emergency ejection systems.
As OP has stated one on hand those systems are expensive, but this isn't the main point why those are not used in commercial aviation. There are two points to consider:

Those systems are heavy. We all have seen how on commercial airlines they weigh your luggage. This is done for a reason - the airplane does not have infinite weigh capacity. If we equip standard commercial plane like Boeing 777 with eject seats there will be no free weight capacity for either passengers or their luggage. One such system (the one I have studied) weights appx 80-90 kg. Seeing standard commercial seats I'd say their weight is no more than 10-15 kg (anyone correct me if I am wrong here). However installing such systems could be done for example on private airplanes where the number of passengers is limited and thus there is some free weight capacity, but it still would be bad solution due to second point.
In order to survive ejection procedure one should have perfect health and wear special suit. Let's start from suite - you've probably seen in movies that military pilots wear special suits, those suits are designed to handle two things that happen to you during flight - depressurization and extreme acceleration. Not sure if in any movie it was shown, but this suite actually consists of network of tubes and pads that are being inflated with high pressure air through connection in pilots seat. Why there is a need in such suit? I won't talk about normal flight in those suits as we are talking about commercial airline, let's see what happens during ejection. When one is ejected, their seat is basically being launched with a rocket engine, in order to prevent damage to pilot/passenger from any parts of aircraft, he/she should be moved away of it very quickly, this means very high acceleration rate. On the other hand our body contains big amount of liquids. Now imagine what would happen if suddenly kick a glass with water? Inertia will hold liquids from moving together with glass, that means all blood in case of ejection will move down in our body - 1) leaving our brain without oxygen supply; 2) destroying blood circulation systems in bottom half of our body. With special suit (that with extra pressure on our body balances this effect) we can make sure that our body will not burst itself out with high pressure blood from below chest level. Although I myself never went through such examination, while studying we learnt that one of very important health checkups for pilots is their cardiac system, means that their heart and blood tubes will be able to handle such an extreme procedure (and this is why running is an important part of military training as it strengthens whole blood circulation system). Still having said all of that about military pilots, more than half of them while will survive ejection procedure, will blackout for some time due to low oxygen level in brain. Also as we were told while studying, even with all this training and equipment people who once went through ejection in mid-air are usually not piloting after that due to damages their body suffered (this info maybe outdated as eqipment we learnt was about 10 years old at that time). Now compare trained military aviation pilot equipped with compensation suit to the average commercial airline passenger who perhaps smokes, eats high cholesterol food and doesn't do much sports ;) What do you think will be chances of survival?

This Incident is not well known so I would like to add Philippine Airlines Flight 812 also (see ASN) to this Question. Technically it is possible referring to this Incident.

The hijacker demanded the passengers place their valuables in a bag
  before he commanded the pilot to descend and depressurize the aircraft
  so that he could escape by a homemade parachute.
Three days after the hijacking, the hijacker was found dead, his body
  nearly buried in the mud, in the village of Llabac, in Real, Quezon,
  about 70 kilometers southeast of Manila, near the border with Laguna
  province. It is speculated that he survived the fall but was killed by
  the mud

Edit because of constructive comment:
Of course this Incident shows that many factors like depressurizing the aircraft and low flightlevel is needed. And as kangacHASHam mentioned, the factor that you can be hit by the tail is quite high.

This does not really answer the question. while showing that a single person might jump, does not constitute evidence that all the passengers and crew might escape safely if needed.

This does Answer the question insofar as the Single Person Had far better chances of survival than passengers in Case of emergency. And Yet he didnt make it...

As an alternate answer in that you can still get parachutes on a plane, even if the airline doesn't provide them...we had a related question over on Travel.Stackexchange.  While, as you noted, airlines don't typically provide parachutes, the TSA specifically allows you to bring your own.
Are parachutes allowed on airplanes as cabin baggage?
Short version from the TSA:

You may bring skydiving rigs with and without Automatic Activation
  Devices (AAD) as carry-on or checked luggage.

That is true, but I think it's important to note that permission exists so that skydivers can travel with ther rigs to faraway dropzones and not have to trust their precious gear to baggage handlers. I've carried a skydiving rig many times as cabin baggage, but I've never seriously considered the possibility that I might be able to use it in an emergency. If the aircraft was crippled and you saw a slim opportunity to save yourself, you would not be able to open a door - even if it were physically possible, cabin crew would still not permit it because it would endanger everyone else on board.

The technical answers have been great, but there is one very simple answer to why airlines don't provide parachutes:
It implies that commercial flight isn't safe
For the similar reason that car's don't protect you to the nth degree, many people will stop using them as they'll realise just what they are actually doing, and as pointed out in another answer the margins are so low that a 10% drop in passengers would be ruinous to many airlines.

I don't agree that adding safety measures implies that something is not safe. They do provide emergency slides and life vests. Isn't that basically in the same category?

No of course not. Telling my wife that is some situations she may need to put life jackets on herself and two kids snd slide down an inflatable slide to ground or water is one thing. Saying there's a chance she may need to get them into parachutes and jump out with them as a plane hurtles to the ground is another, having parachutes reminds them constantly that this may happen, and many will start to think twice.

By that argument, car sales should have dipped after airbags became standard.

No, there is no similarity.  The point isn't adding safety features (airbags are a balloon in most people's eyes), it's reminding people that they are miles up at high speeds and their safety/existence is totally reliant on the metal tube they are in.  Many people don't want to think about that.  A better analogy would have been to offer parachutes in skyscrapers in case of 9/11 style attacks, many would think twice about going to high floors.

I think its a more of a materials and technology issue. We don't have parachutes in airliners and space shuttles because of practicality issues with today's parachutes designs and materials and weight-balance issues on the aircraft..
If you can design a very light parachute that can be integrated with oxygen mask, life vest, and thermal protection all in one piece, that you could fit into the airline seat that you are already seat belt strapped to, and be ready in 5 seconds or less, why not?
The astronauts on the Challenger disaster were alive in the craft until it hit the ocean. All while high altitude balloon pilots had already demonstrated safe descent from the edge of space in pressurized suits with parachutes in the 1950s.
Will they get hurt exiting the aircraft or spacecraft? maybe, maybe not, every situation is different.
Contingent on having the above practical parachute technology. Typical scenario:
If the aircraft is flyable but not landable, say engine failure or fuel problem in middle of ocean, the pilot can maintain slow glide a few knots above stall, so passengers can get ready with said parachute integrated survival gear in their seat back and exit rear doors behind the wings, the parachutes would automatically deploy as soon as they exited. The stewardesses and non-flight control crew would follow. The pilots would do the same only after making sure the plane would ditch itself into the ocean a safe margin afterwards.

In the case of airliners, I'd say technology constraints are still the least of your problems. Even if you can overcome the challenges of designing affordable parachute gear that can be safely attached to passengers (of all ages, shapes and sizes), and even if the aircraft is flying at a survivable speed, and even if you can manage to open a door, many of those passengers will probably be too afraid to jump and will be in the way of those who are not. Also, in your scenario of baling out over the middle of the ocean, exiting the aircraft successfully would only be the first part of the ordeal.


text:
How do you catch a runaway blimp?
A few hours ago, a rather large (243 feet long) helium blimp owned by NORAD broke loose of its moorings in the Eastern United States and floated away. The news is currently reporting that it's being "escorted" by a pair of F-16's as it floats along at 15,000 feet, and is currently somewhere over Pennsylvania. (Next state over from where it started, at the Aberdeen Proving Grounds in Maryland.)
Given this situation, what are the military's options for recovering this blimp? Do they have to wait for it to crash land somewhere eventually (when it runs out of wind, I suppose?) Or is there some other option for them to "catch" this blimp given its size and the fact it's pretty much under nobody's control?
Here is an article about it: "JLENS blimp has come free of its tether at APG, now floating over Pennsylvania; fighter jets monitoring." The Baltimore Sun. 28 October 2015, 14:34 ET.

Edit: In case anyone is curious, the blimp landed in Pennsylvania a few hours after I posted this question.
Miklaszewski, J. "National Guard to Shoot at Crashed Blimp to Help It Deflate." NBCNews.com. 29 October 2015, 14:32 ET.

I'm also trying to imagine how f-16's are managing to escort a free-floating blimp

Perhaps relevant:  Does the blimp carry any military equipment that should not be shared with downwind neighbors?

@TomMcW It certainly has a distinct Simpsons feel to it

How is it opinion based? I'm asking what options there are available, not the "best" option or the one that "should" be done.

I'd take off and nuke it from orbit. It's the only way to be sure.

@TomMcW I'd imagine they spent a lot of time going in circles.

@TomMcW https://www.youtube.com/watch?v=Yu_eTG560eg

@robert Love it! Never seen that episode.

FYI the news making the rounds now is that the blimp was brought down by an unknown number of shotgun shots from the ground.

Really? I heard that it "deflated" last night, causing it to crash in a field, and today they're (army or state police depending on the report) is trying to deflate the rest of it using shotguns.

Another incident like this happened over the Florida Keys in 1981/82. The blimp that was carrying a radar to watch for drug aircraft coming north from South America broke free, and F-4Ds from Homestead AFB were scrambled against it. Since it emits no heat AIM-9s were useless, and authorities were concerned about shipping should a 500 lb. AIM-7 just go ballistic and fall into the Gulf of Mexico, so the aircraft were directed to use their 20mm Suu-23 Gun pod against it.

Historically, a runaway airship cannot be caught or entered. Eventually it will come down - they all did so far. Only in one case did a Zeppelin fragment of a ship which broke up in a storm make a soft landing so the crew aboard could survive. In all other cases both ship and crew perished or were never seen again.
While the Zeppelins had vertical shafts which allowed the crew to climb to the top of the hull, a blimp can only be entered below the hull. Trying to lower someone James-Bond-style from above will fail, because the big hull will shield the entry points of the gondola very effectively.

Defensive gunner position on a Zeppelin. Note the square hatch at the bottom which leads down to the bottom of the ship.
Also, shooting it down will be an exercise in futility. All it will do is to increase the rate of helium loss, so the flight will be some hours shorter. Helium is inert and will not burn, and those small holes will be tiny relative to the big surface of the hull.
At 15,000 ft it will be hard to try to catch one of the lines most likely hanging from the blimp with a helicopter. Remember that the blimp floats, so the helicopter has to hover at this altitude. Very few are able to do so. Towing will only be possible with another blimp or a helicopter; an airplane will not be able to fly fast enough with a blimp in tow.
The next trick depends on the color of the hull: If it is dark, covering it with something highly reflective will cool it and reduce the blimp's buoyancy. I have, however, no idea how to get a big blanket on that thing. The same will happen when night falls, but first the air will cool and the blimp, which will cool down more slowly, will go up. Later in the night and early in the morning it will sink again.
The wet parts of rain clouds will mostly be below 15,000 ft (water content is proportional to air density, after all), so a shower which drenches the hull and makes it heavier is highly unlikely. There is no obvious way how this thing will come down fast. Except, that is, it climbs further and the hull bursts. This will change the dynamics of this escape in a dramatic way.
The chase planes will help ATC to route traffic around the blimp, and all that can be done is to watch it. With luck the landing will be soft enough that it is not a complete write-off.

Umm, lots (even most) rain clouds are higher than 15,000 ft.  I fly through them all the time.  ;-)

@Lnafziger: Yes, the tops of the clouds, but not their bottoms. Remember, the blimp cannot fly into a cloud because it moves with the air. Either the cloud forms around it or it climbs into it. And for rain to soak the hull, the rain needs to rain down on it. Only if a cloud has formed above or around it and produces enough rain (which only works at low altitude) will it get wet.

What if they flew over it with one of those fire fighting aircraft and dropped a few tons of water on it?

Assuming you did get a helicopter in position, how exactly would you catch one of the lines without it getting tangled up in the helicopter's propeller?

Can you reach the gondola by hanging onto two ropes, one from each side? Or would it be too dangerous for mr. James Bond?

@user2813274: Fly above the airship, lower someone on a rope down to the line and let him grab it. Keep the rotor above the airship at all times.

@JanDvorak: The ropes will hang straight down from the sides of the envelope, quite a distance away sideways from the gondola. James Bond could try to swing on the rope until he can grab the door handle, but I expect this will work much better in a movie than in reality.

I mean, have two high altitude planes connected by a long cable with James Bond hanging in the middle. The cable flies under the blimp, them climbs towards the gondola (either the planes fly up or they fly apart) until James Bond can grab it and save the day. Is that at least remotely plausible?

All we need is a Zeppelin. A Led Zeppelin.

@PeterKämpf "two high altitude planes connected by a long cable" -- What, held under the dorsal guiding feathers?

@Random832: The two planes with a cable are the idea of Jan Dvorak so you should address your comment to him. I am sure it will not work because the planes have to be fast, and the blimp is stationary. Poor James will either miss the gondola or slam into the blimp at full speed.

One could use a V-22 Osprey and lower someone onto it, attach it to the aircraft then nose down and carry it with it. The osprey can fly slow enought and high enough to meet the blimp, it has a back door and enough space to carry a very large cable, along with the devices to lower people onto the blimp. It also is large enough to easily tow it and does not have the "blades close to the cable" problem that an helicopter would have. The osprey can full-hover at 14,000 feet, however, in slow forward speed it can reach much higher, making it ideal for this job.

I've never seen a job I envied less than gunner on top of a zeppelin.  You can be shot while falling AND burning to death.

@EricHauenstein: When the war started, Zeppelin crews felt on top of the world. They had the most prestigious jobs and a good life, too. Then airships started to explode (with or without enemy action) and their job turned into a nightmare. The even went as far as to sabotage their ships in order to stop flying them.

That would be an odd sight for passengers on nearby airliners, to be sure...
The options for dealing with a runaway like this depend on the airship's cost and capabilities. This particular blimp appears to be closer to a balloon; no propulsion, no on-board piloting capability, basically its job is to face the prevailing winds coming on from the Atlantic allowing the radar in its gondola to scan for incoming cruise missiles (and track ships at sea and cars on the roads in DC, apparently; at least it's capable of doing so).
If it were an ordinary camera balloon, like the ones forming a part of the "virtual fence" along the U.S.-Mexico border, the F-16s would likely have already been given the order to take it out with a burst from the 20mm. The problem with this blimp is that it's one of two prototypes resulting from a $17 billion R&D project; they're not just going to shoot it down like that unless it's the very last option to prevent the blimp leaving U.S.-controlled airspace on its way to Canada (and, eventually, Russia).
The best option would probably be to approach it with something a little slower than an F-16, either a manned blimp or a slow, long-range prop job, and get a hold of the blimp with a tow tether. The blimp could then be towed back to Aberdeen (or any nearby airstrip). The technical issues would be daunting, though:

Getting hold of the balloon from another aircraft at 15,000 feet without a collision or other damage to either aircraft is harder than it sounds; you can't just calf-rope it.
The balloon isn't designed to be towed at any appreciable speed; you'd probably have to use another blimp, something able to make headway against the wind but at a slow enough airspeed that the towed blimp doesn't come apart. The U.S. military doesn't operate many manned blimps in the 21st century.
The balloon doesn't appear to have been designed with any altitude control in mind; this means whatever other aircraft tows it back to Maryland is going to have to pull it down from 15,000 feet against the force of lift from the blimp's gas bag. This may require the towing aircraft to more or less hang from the tow tether, which isn't guaranteed to be secure.

Honestly, the safest solution sounds like taking up a skydiving aircraft with a sniper, everyone on oxygen, and having the sniper shoot the balloon to cause a slow leak of its helium. The remaining problem is that the balloon is too high to get back on the ground before its entire helium supply is gone, so if the blimp doesn't have a ballistic parachute, you're going to lose a very expensive radar gondola.

From the article: They're designed to stay aloft in winds of up to 70 knots, and remain in the air even if their skin is pierced. Sounds potentially able to be towed but difficult for a sniper to take down.

@fooot - For how long, though? A hole in the skin is going to leak helium, so even if the gas bag were rip-stop nylon and it had a backup tank to replenish leaks, it would eventually have insufficient gas to maintain lift, especially at 15,000 feet. If the blimp has individual cells of helium under the skin, that's actually better, as a sniper could take out just enough of the cells that the blimp couldn't maintain lift, instead of one hole emptying the whole bag.

Ok, good point, so potentially better on both counts.

You'd be surprised how little a burst from the 20mm cannons will change.

Shooting bullets or (much worse) a 20mm gattling gun at a target like this has the problem of how far the rounds go & where they eventually hit the ground. "Big Sky" theory says that the probably won't kill anybody, but that isn't really good enough to go making gunnery passes outside of a restricted area!

Very true, both of you. I'd imagine, if the order were given, that the F-16s would try to line up such that their rounds' trajectory is toward wilderness. However, a round exiting at 3,450 ft/s with a designed shotgun spread (roughly aircraft-sized at 1000 ft) and then falling 15,000 feet is not going to be as predictable as anyone would like. But, what other weapon would you have on an F-16 that would do the job? A Sidewinder might not even see the blimp reliably enough, and an AMRAAM is a million-dollar insult to injury (and it has a considerable minimum range).

Only other thing I can think of is deliberately crashing a UAV like a Predator drone into the blimp, and that would be just as difficult to control and to manage falling debris. And, RQ-1s are $4 million apiece.

Drop black paint on it from a firefighting aircraft and let the sun heat it up, so it climbs until the hull bursts. Or hang some razor wire from an aircraft and make passes above the hull so it gets some long cuts. This will bring it down more quickly than any gun.

Could work. You'd have to deal with some irate people on the ground whose house or car was covered with a fine mist of black paint (maybe it can be water-based so it'll wash off). I was also thinking that a major loss of lift like the gas bag bursting or being slashed open would cause the radar gondola to come crashing to earth with even more kinetic energy than a bullet; Big Sky theory again, assuming it probably won't hit anyone, I'd still take a slow, semi-controlled descent over a crater in the ground.

@KeithS, based on Goodyear's experience with rednecks taking potshots at their blimps, a single bullet hole (or even a few magazines' worth of bullet holes) will take a few weeks to bring it down.

Yet another problem for which the simplest solution is "more dakka" :)

@RalphJ shoot it from the air. That solves the range issue and should also take care of accuracy.

Petty point, but since NORAD is a cooperative effort between Canada and the United States, I doubt they'd shoot down expensive equipment just to stop it flying over Canada. Perhaps I'm wrong, obviously the actually decision making factors are not public knowledge.

A blimp does not have an internal structural framework or a keel and relies on the pressure of the lifting gas (usually helium) for lift. It is basically a huge helium balloon and a way to bring it down is to release the gas by puncturing it.
There is no (safe) way to catch a blimp as the only entry point is below the gas bag. The best option is to shoot it down using incendiary bullets. During WWI, firebombs were used against Zeppelins (though these were filled with hydrogen, not helium).

How would incendiary bullet be better than normal bullet since this is Helium balloon, not Hydrogen one?

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What is the proper procedure after a bird strike in a single engine plane during takeoff?
First, let me set this up and then ask a general question.  I'm just trying to give some context as to why I'm asking.
I'm working on my private pilot license and was practicing with my PC simulator (X-plane) this weekend.  I was flying a Mooney m20j out of John Wayne (KSNA, which has two runways, 16R/1L 16L/1R).  I took off from 16R and at about 300AGL I encountered a bird strike and my engine died (though my windshield was intact).
I was just about at the end of the runway so I declared an emergency (yeah, I've been talking to myself...) and said I was going to turn the plane around and land on 1R (so, the parallel runway in the opposite direction.)  I was kind of panicking and had no idea what to do, this was just the first thing that sprang to mind.
I started the turn and quickly realized I was sliding sideways towards the ground, so I leveled out the plane a bit and ended up making a short approach on a taxiway, which I managed to land (though that may be down to the simulator being a bit forgiving and not me, really.)  So the plane survived...

So I've got two questions, the first a little specific (though I'll try to generalize it) and the second nice and general so it applies to a wider audience.

Is the process I described a good approach to a bird strike during take off?
In review, I feel I probably would have been better off just landing straight ahead on a road or open field, but I thought I'd ask.
What is the best way to deal with a bird strike or incident on takeoff that fails the engine?
I'm particularly interested in situations where the plane is about at the end of the runway - if it happens right as you take off you can just put it back down, and if you're much higher up you have a lot of options because you can glide for a while.  But right at the runways end, when you have very little altitude and no more runway...  What's the proper procedure?

"if it happens right as you take off you can just put it back down" -- you don't have any choice!

"glide for awhile" -- at 65 knots best glide, the glide ratio is (generously) 10:1, so at 1,000ft, you have about 10,000feet of straight ahead glide, and less than 2 minutes to find your spot. if you turn back to the runway at 500ft, you have <1 minute, which is not enough to make a 180 standard-rate turn

+1 for declaring an emergency to yourself. Also for a pretty nice question but mostly the first one.

@NathanTuggy - My head was just so in the moment that declaring an emergency just kind of came out ;).  The real strange thing was I was so "into it" that the bird strike seriously freaked me out, my heart rate was elevated for at least 20 minutes.  And, last I checked, my simulator is still just pixels on a screen...

The first question listed as related, http://aviation.stackexchange.com/questions/786/is-it-even-remotely-feasible-to-turnback-a-single-engine-aircraft-with-an-engine, is indeed very relevant here. The point is, you have to know the altitude from which the turn is possible and should practice it if you want to manage the required tight slow turn without stalling.

A comment above refers to best glide as 65 knots. This is completely dependent on the type of plane. I think 65 knots is best glide for a Cessna 172, but best glide in a mooney m20j is probably more like 90 knots (105 mpg).

Why would a bird strike take out a 180-200 horse power engine? That doesn't seem realistic.

General rule of thumb: ANY aircraft will lose a lot of altitude gliding through a turn; if you only just took off, you don't have any to spare. The best you can do is a shallow bank to tweak your heading a little to line up with your chosen landing spot.

You will not find a "single rule fits all" but in general, on PPL training, you are taught < 700 feet, land ahead no matter what.
A skilled pilot, with good currency, in an aircraft they know well, in good conditions they have planned for and with enough altitude, might successfully turn around.  Another pilot in the same aircraft with the same conditions might kill themselves.
The consequences of getting a turnaround wrong are worse then getting a straight ahead landing wrong and, by turning around, you might very well put someone else at risk.  You have much better prospects mushing down straight and level into those trees ahead than stalling out of a turn in an attempt to get back to somewhere you may or may not make.
Forget the flight sim heroics.  Nose down aggressively for best glide (you should already know what that looks like!), then start looking, or even better, go for the area you know is good because you pre-planned for an EFATO.
Bottom line, when you do start training (good luck!), do whatever you are trained to do.

Excellent, thank you!

@rbp I do not agree with a couple of apsects of your edit, one factual, one grammatical so I have made further edits.  You do NOT pitch for best glide first.  The training should be instinctive for initial actions and that is nose down aggressively, then adjust for best glide.

"If an actual engine failure should occur
immediately after takeoff and before a safe maneuvering
altitude is attained, it is usually inadvisable to attempt
to turn back to the field from where the takeoff was
made. Instead, it is safer to immediately establish the
proper glide attitude, and select a field directly ahead
or slightly to either side of the takeoff path."
http://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/airplane_handbook/media/faa-h-8083-3a-7of7.pdf

pushing the nose down aggressively will result in a plunge, which will cost you precious attitude. didn't your CFI cover this in stall recovery?

Flight training says "nose down" to avoid a stall and look ahead for a good landing field. You should probably aim at something like best glide, if you know the aircraft, but your number one priority is not get into a stall, because that's the end of it at these altitudes...

if you don't know what Vbestglide airspeed and attitude is, you're not qualified in the aircraft

@rbp Agreed, but that's not how PPLs are trained.  High power, steep attitude, engine fails.  Instant panic.  Now what was that speed again?  And let me push the nose down until the sight picture is correct.  Nope, correct IA is nose down aggressively, then sort it out.

while you're "sorting it out" 400 feet below me, i've already got my place picked out to land and am running the before landing emergency checklist (you do have that memorized right?) What you'll find, if you had any airplane time, is that when you're climbing out at 80, have an engine failure, pitching for 65 will keep you out of the stall region AND you will be converting the 15 kts of airspeed into a little more altitude. if you pitch the nose down aggressively, you'll find you've just lost 400ft and you're doing 80+kts again.

"sample takeoff briefing that I would use in a single-engine aircraft:
This will be a normal takeoff.  We will departing on runway 24 with an initial altitude of 3,000.  Vr is 50 and Vy is 67.  If we have any problems before rotation or with adequate runway remaining after liftoff, we will abort.  Standard emergency procedures will be used in the event of engine failure without adequate runway remaining.  Best glide is 65 KIAS.  We won’t even think about returning to this airport unless we are at 1,000 AGL.  Any questions or comments?" http://www.askacfi.com/618/sample-takeoff-briefing.htm

I was taught that if you have an engine failure on takeoff you race the tachometer needle down to zero while simultaneously looking for the landing spot you picked ahead of time (you do know where you're putting the plane, at least at your home field, right?). If you drill engine failures in takeoff configuration at altitude you'll find it is a pretty aggressive push to go from a Vy climb to best glide speed, and you should do that until you have a feel for what the "push" should be. It's not easy to push too hard, but you don't want to push so hard you accelerate through best glide speed.

@voretaq7 if by "aggressively" you mean "swiftly" I'm all for it. the interesting thing about Cessnas and Pipers is that Vbestglide is about 5 knots above Vx. In a Cherokee 180, Vx is 76 and best glide is 80. In the 172, Vx is 60 and best glide is 65. Glider pilots will understand this immediately because of polars http://en.wikipedia.org/wiki/Polar_curve_%28aerodyamics%29

@rbp exactly - In light planes where Vg and Vy are the same (or very close) you're likely either at or below best glide speed on takeoff. If you don't push the nose over immediately when the engine stops your airspeed WILL decay well below best glide speed pretty much instantly. If that happens you're sacrificing distance the same as if you push too aggressively (and if you don't push the nose over heading for a stall that will cost you even more distance/altitude).

Mostly this argument is funny to me because you all agree and mostly you're arguing semantics....just fyi.  I read the initial answer to mean "nose down aggressively to best glide", but hey...

I think it's worth making explicit that the reason for the engine failure is largely irrelevant. In other words, the whole "bird strike" part of the question just doesn't matter. If your engine quits at low altitude you will be spending your effort on landing safely and not on figuring out why it quit; that can be done after you're safely on the ground.

A real life emergency is not a chance for trying unnecessary risky moves, especially new ones.
One of the AOPA seminars (I forgot which one) actually mentioned such a situation: an engine failure very shortly after take off in a GA plane. They did some tests in Microsoft Flight Simulator 2004, executing the 180 turn with varying degrees of bank. In the sim, if you bank steep enough (at least 60, or even 75), you have a good chance of making it to the runway. But then...
In real life, when you bank, you increase the stall speed. Worse, if you feel you can't make the turn, you may be prompted to pull back, increasing your stall speed even further. Now, you end up with a accelerated stall at a steep bank, engine failure, and very little altitude to work with!!
The best approach is to try at perhaps 3000 feet. Apply takeoff power, pitch up to take off attitude, then pull back throttle to simulate a sudden loss of power (don't forget to clear the area of traffic beforehand). Work out how much altitude is necessary to execute the turn, which varies from airplane to airplane.
When flying, it is best if you have a predetermined turn/no-turn altitude. If you don't know, either figure it out or ask your instructor. There is very little altitude, and very little time to think. If you're below that altitude, don't think about it, land straight ahead.
My instructor, who is an aerobatic pilot, can perform a "stall turn" (a.k.a. "hammer head") to turn the plane around. If executed correctly, the plane should end up in the opposite direction with almost no lost of altitude or speed. Bear in mind, though, this is because he has done this many many times, so he is confident to execute it a low altitude. Do not try this if you have never done it!

When I took the SIMCOM course for the PC-12, we practiced upwind engine failures from 800ft, which had been successfully accomplished in real life. It took a few tries, but it was certainly doable. The current literature from Pilatus says its possible from 1,000ft, and I would concur. http://www.pilatusowners.org/wp-content/uploads/2012/07/Summer2011_POPA_Magazine.pdf (page 13-15)

Depends on piloting skills and experience I guess. If I were to take up a new (no previous experience) airplane  and test it, I'd want at least 2000 ft. Not that I intend, but just in case I managed to stall it (or even worse spin)...

The situation you describe is an engine failure on takeoff and your response is going to depend on the glide characteristics of the airplane you are flying.  Most light aircraft require about 1000’ of altitude AGL before safely attempting a turn to a landing site 180° from current heading.  Attempting to do otherwise leaves insufficient altitude available to execute the turn in.  Worse yet, pilots have a tendency to pitch for the desired landing site and/or increase their angle of bank in order to expedite the turn, often resulting in an invariably fatal stall/spin accident at low altitude.
The general procedure for an engine failure (and it should be part of a before takeoff briefing) is as follows.
1) DON’T PANIC; FLY THE AIRPLANE!
2) If engine failure occurs >3000 ft AGL, attempt emergency engine restart procedure checklist, if <3000 ft AGL commit to a forced landing.
3) Pitch for best glide speed.  At low altitudes in a climb you may have to do this very rapidly to prevent a stall.
4) GEAR - down and locked
5) THROTTLE - idle
6) PROPELLER CONTROL - max pitch/min speed
7) MIXTURE - Idle cutoff
8) IGNITION - Off
9) FUEL SELECTOR - OFF
10) FLAPS - as required to make landing site
11) Select Landing site: 0-300ft AGL land straight ahead, 300-600ft AGL select site +/-30° off the nose, 600-900ft AGL select site +/-90° off the nose, >1000ft AGL select site anywhere in vicinity of airplane within gliding distance including returning to the departure airfield, if able.
12) ATC - Declare an emergency and state intentions
13) IF TIME AND WORKLOAD PERMIT, complete ENGINE FAILURE ON TAKEOFF and/or FORCED LANDING checklist.

Doesn’t gear down/up vary depending on the aircraft?

It has never happened to me, but in Spain we have a surplus of birds of all sizes, and the big vultures do usually insist in their right-of-way...
I believe that the first thing to do after a birdstrike is to try to keep calm and continue flying the plane straight and level. If the engine and the controls work, you should try to find a good place to land, but keep calm, above all, and fly the plane. If there is clear structural damage, you should land immediately, on any not-too-bad place you may find ahead, but it's better not to be picky... And don't forget to radio a mayday...

Most times when there is a birdstrike in a propeller aircraft, the engine won't fail (I've never heard of it happening).  However, a proper takeoff briefing should be done prior to every takeoff with ANY crewmember, this includes the flight instructor and student.  My takeoff briefing in the Cessna 172 was, "Rotation speed is 55 knots, if engine failure prior to 55 knots, we will stop on the runway.  If there is an engine failure above 55 knots and we are airborne, we will reland if there is enough runway remaining.  If not enough runway remaining and we are below 1,000 feet AGL, we will land straight ahead.  Anything above 1,000 feet we will look for other fields, most likely returning to the airport.  Questions?"
Now I want to point out that I've practiced engine failures in a Piper Archer (similar v-speeds to the Cessna 172) on the upwind leg.  At 700 feet AGL, I reduced power to idle immediately turned around and made the field.  However, in the event of an actual engine failure, I would never turn around below 1,000 feet AGL.  This is due to a couple of reasons.  Firstly, when I "killed" the engine at 700 feet AGL, I immediately turned towards the field.  I did not allow time for my brain to process what had happened and made the decision like I would in an actual engine failure.  In addition, I took off with an 11-knot headwind which helped me keep close to the runway on the upwind leg and helped push me back to the runway when returning.  I'm not sure if I would have made the runway in a calm wind scenario.  I also tried the same failure at 700 feet AGL with a tailwind departure.  This made an 11-knot tailwind on the upwind leg and 11-knot headwind on the return.  I would not have made the runway and had to add power to keep me from landing in the grass about 500 feet from the runway edge.  Lastly, even with the airplane at idle power, it is still producing some, very little I will admit, but some forward thrust.  So I'm sure this little boost of thrust helped me return to the runway.
I would like to add I've seen people with engine failures in real life, that made the runway from 1,000 feet AGL or better in single-engine aircraft.  Also, I witnessed first hand a multi-engine airplane try to turn around at about 800 feet AGL and entered a VMC roll and crashed nose first into the ground killing everyone on board.  Moral of the story, practice for every scenario and do what you think you and the aircraft are capable of.  Your job as a pilot is not to save the aircraft, your job is to keep the people on the plane alive.  So don't try to make a runway if you know you can't.

Treat the bird strike question and the engine fail question as separate issues. Like a previous poster said, most bird strikes do not cause engine failure.
I have personally seen one bird strike and participated in another bird strike. Neither stopped the engine. For our Class D airfield, the SOP would be to notify ATC (or, CTAF after hours) to warn other pilots of the danger. If the bird strike happens over the runway or other movement areas, mentally mark where it was so that grounds crew can search the area for organic and inorganic FOD. In some areas, the carcass has to be retrieved so that the species can be identified. Especially near environmentally sensitive areas or protected wildlife. Then, land as soon as practicable to inspect for damage and check all air inlets.
Now, if the engine stops, follow your engine out protocols and checklists. These should be memorized. Because, you won’t have any time when it happens.
A good memory aid is:
A is for Airspeed - immediately pitch for best glide. Then trim.
B is for Best landing area - be on a constant lookout while the engine is running. Head for it. Don’t vacillate between alternatives.
C is for Checklists - After A & B, then run your checklists (time permitting).
D is for Declare an emergency - while you still have altitude.
E is for Electricity - all off after landing is assured and configured.
F is for Fuel - off after landing is assured or immediately if there is a fire.
G is for Get Out - ensure your egress by propping doors ajar before touchdown.
H is for Haul something - after it comes to a full and complete stop, exit the aircraft a far enough distance to be safe from harm. But, close enough that rescuers spotting the aircraft will also see you.
If you can just remember the first four, make it muscle memory. You won’t have time for anything else.
If this is on takeoff, you should have briefed the best landing areas to yourself and crew right before taking the runway. Review the A/FD Chart Supplement, and satellite imagery in your flight planning. Ask other local pilots. Ask the FBO. Just be prepared.and know your particular Possible Turn altitude.

Your general list of priorities will be as follows:

FLY THE DAMN PLANE. Your aircraft's documentation will note a "best glide" speed, I suggest you trim for that. Smoothly. No need to make it worse by panicking and/or focusing purely on the engine loss.

Land at earliest convenience. If you have the altitude - turn back and head for the runway. You may have to just do a 180 and land backwards (whether the winds are favourable or not), but ideally you'd do a tight circuit, suitable for your remaining altitude. If you don't have the altitude, pick a field. I mean that. Turning back will just have you land short, so pick somewhere nice and flat, and keep it steady. It's preferable to land on a proper air strip if possible, but if it's not, your ultimate goal is to be able to walk away from your landing.

It is generally advisable to advise ATC (if available) and/or other traffic on the same frequency and in the same area that sh!t's gone down and you're going down with it. Maybe you get the time/capacity to do that... maybe you don't. Maybe a bird kills your engine 50ft above a very long runway and you "abort take-off" there and then.

More than anything else though, discuss this with your instructor and heed the advice. Under normal circumstances this sort of thing would be planned for on the ground, so ideally you'd never be in a position where you have to improvise. It's a good skill to have (I'd argue indispensable), but it's never something you want to have to actually use outside of a training environment. There should always be several layers of planning between your actions and figuring it out on the spot.

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text:
How can I know where wind is coming from by looking at water?
For ground reference maneuvers, I know there are many ways that I can know wind direction: smoke, circling, weather reports from nearby airport and so on. However, how can I determine the wind direction by looking at water? I've tried to look for detailed explanations about it but I have found nothing useful. Can somebody help me to understand this issue? I would appreciate if there is any graphic materials.

The easiest way to tell the direction of the wind when you're near the water is to look for something on the shore that indicated wind direction (beaches often have flags on them)
Barring that there are a bunch of other clues that should be familiar to any sailor (or seaplane pilot) which you can borrow:

Boats lying at anchor weathervane and automatically point into the wind
This isn't 100% reliable: Some boats will set two anchors (fore and stern) and won't weathervane. Also when the tide is shifting boats will swing to align with the tide if it's stronger than the wind.
Boats lying at anchor sometimes have a flag on them
Flags on a boat at anchor work the same way as flags on land - they're excellent indicators of wind direction.
On calm bodies of water the wind creates visible surface ripples
The concave side of these ripples is the windward side.

(Visualize the water as being a large bowl of soup - now blow on the soup. The ripples will have the same shape.)
This same principle applies to larger waves as well (other factors could cause the dominant breeze along a shoreline to not be quite perpendicular to the waves, but if your concern is ground reference maneuvers it's "close enough").
"Wind Streaks" on the sea indicate wind direction
Wind streaks are somewhat ambiguous in that they're aligned with the wind, but don't tell you which way it's blowing: You have to figure that out for yourself (for example by looking at the shape of the waves as described above).

Surf spray gives wind speed and direction
Waves breaking will produce spray that blows downwind - I couldn't find a good illustration for this, but the finer spray tends to blow, while heavier drops just fall. The distance the spray blows gives an approximate indication of wind speed.
It would take some pretty heavy seas to produce visible spray at altitude though, and you're more likely to see foam and whitecaps in that case
Foam or Whitecaps provide wind speed and direction
Foam or whitecaps provide an indication of direction (the foam appears to move upwind - into the wind) and speed (it generally takes winds of 10-15 knots or more to produce whitecaps and foam).

There's a little bit about this in Chapter 6 of The Seaplane Handbook (landings), which is where I cribbed one of the "wind streaks" image from. Their explanations may also be helpful, but the content wasn't as deep as I was hoping for.

Waves move in the direction of the wind, and form long lines.
Cresting waves always break downwind & whitecaps are generally pretty easy to spot.
So look for parallel lines of waves.  A line perpendicular to the wave-line will be directly-into / directly-away from the wind.
If the waves are very large or moving very slowly, it may be hard to determine which direction they're moving, but at least you'll have an axis for the wind direction.
If the water is calm enough that you cannot figure out wind direction, it generally means there isn't much wind to speak of.  It generally only takes a couple knots of wind speed to make discernible waves.

Note that, on large bodies of water (oceans, seas, large lakes), you might get swell moving in a direction that doesn't match the local wind.

On inland bodies of water (lakes, ponds, etc.), as the wind blows across the ground the water will be calm on the side where the wind blows from.

It's hard to get a good photo with an iPhone at 10,000 feet, but this shows a pond with calm water on the left and waves on the right. The wind blows from the left. This photo was taken close to sunset so the difference in surface characteristics of the water is pretty dramatic, but this can be seen in just about any light.